Hello, and thanks for answering the poll.
The point of this questionnaire was that when scientists were asked this question, the majority (I don't remember the numbers now, but I think it was something around 70 - 80%) said that they thought the sea ice extent in 2013 would be higher. Which makes sense, because of 'natural variability'. In the non-scientist general public, however, the majority answered 'less sea ice'.
The figure above is courtesy of Årthun et. al. 2012; nsidc.org. It shows the modeled sea ice area in the Barents Sea, north of Norway. In the Barents Sea, the sea ice melts completely during summer (hence you see that the non-smoothed data (thin blue line) go down to about zero once a year), so this is not representative of the total sea ice in the Arctic. However, the trend is roughly the same.
The trend is indicated by the thick blue stipled line, and is really just the difference between the average value at the start of the time series, to the average value at the end. Note that in a climatological perspective, this a short time series.
The thick blue line is a smoothed version of the actual data, and the actual data is the thin blue line. What is interesting in this context are the peaks of the thin blue line (You can imagine a line connecting all those dots). Some years they are lower, some years they are higher. Though, during the period, the minima and maxima of the peaks goes down, according to the trend.
This can be transferred also to the minimum sea ice extent of the entire Arctic ocean. The trend will show that it decreases, though some years the minimum will be lower then other years, and some years will be higher. This is the annual variability.
Though this is a short timeseries, compare the peaks of the period 1980 - 1990 (period 1), and the peaks of 2000 - 2010 (period 2). The highest peak(s) in period 1 is (are) higher than the highest peaks in period 2, but the peaks aren't continuosly getting lower for each year. After a low peak, the next peak is usually higher, or the same, and sometimes lower.
The point is, the decrease in sea ice cover is not a constant. It is not continuosly getting lower for each year, but jumps around about a mean decreasing trend.
I hope I did not confuse you to much with this lengthy post! The idea was to test you guys a bit, and hopefully improve your understanding about climate variability! You can apply this to different parameters as well, such as temperature or precipitation (they also vary alot, of course, from location to location, and not just in time). I am not sure about wind, so don't ask me about that. 
*edit: Kazinsal, I see that you are getting into Geology. That is cool. I would encourage you to continue down that path, as I have become increasingly interested in it as well. Just don't end up in the oil business. |
